Film-type ignition element and method for producing same

ABSTRACT

The invention relates to a film-type ignition element, used in particular for igniting the propellant charge of large-caliber ammunition. The invention furthermore relates to a method for producing an ignition element of this type.  
     To ensure that the ignition element can be produced easily and cheaply even with high reproducibility, it is proposed according to the invention that essentially only black powder, nitrocellulose and a plasticizer as binding agent are used for the material, wherein the share of black powder&gt;60 weight % and preferably 63 to 85.5 weight %, the share of nitrocellulose&lt;10 weight % and preferably 2.8 to 7 weight % and the share of the binding agent is ≧5 weight %, preferably 5.0 to 30 weight %.

BACKGROUND OF THE INVENTION

[0001] The invention relates to a film-type ignition element, in particular used for igniting the propellant charge of large-caliber ammunition. The invention furthermore relates to a method for producing an ignition element of this type.

[0002] German reference DE 43 18 740 C2 already discloses a film-type ignition. element that functions as ignition booster and is designed as hollow cylinder fitted around the tail end of a large-caliber projectile which is arranged inside of the cartridge case. This known ignition element contains a high share (approximately 62 weight %) of nitrocellulose and therefore acts as explosive disk, e.g., a bursting disk, or a combustible case.

[0003] Explosive disks require an extremely high production expenditure to obtain a reproducible combustion behavior, which is necessary for igniting the propellant charge. Since the respective ignition booster controls the combustion of the respective propellant charge, even small deviations in the ignition and combustion of the ignition booster can lead to significant changes in the maximum gas pressure of the propellant gases and thus also to corresponding changes in the muzzle speed of the respective projectile.

[0004] It is the object of the present invention to provide a film-type ignition element of the above-mentioned type which can be produced easily and cheaply even with high reproducibility of the combustion behavior and which bums up completely. The invention furthermore is intended to disclose a method for producing an ignition element of this type.

SUMMARY OF THE INVENTION

[0005] This object is solved according to the invention with the features in claim 1 for the film-type ignition element and with claim 7 for the method. The depending claims disclose additional and particularly advantageous embodiments of the invention.

[0006] Essentially, the invention is based on the idea of using a film-type ignition element with a considerably lower combustion speed, as compared to the explosive disks, and a characteristic briskness value L30-80 between 0.1 and 0.3. This is achieved in that the material for the ignition foil essentially consists of black powder, nitrocellulose and a plasticizer as binding agent, wherein the share of back powder >60 weight %, preferably 63 to 85.5 weight %, the share of nitrocellulose <10 weight %, preferably 2.8 to 7 weight %, and the share of the binding agent is ≧5 weight %, preferably 5.0 to 30 weight %.

[0007] To obtain in particular soft and flexible films, which can be wrapped directly around the ignition tube inside the cartridge, for example, binding agents (plasticizers) such as bis(-12-ethylhexyl)-phthalat, dimethyl-phthalat, Edenol B33 and butyl NENA have proven themselves.

[0008] The wall thickness of the ignition element should be between 0.3 and 2.0 mm, preferably between 1 and 1.5 mm.

[0009] To produce the ignition elements, nitrocellulose can initially be mixed with the dry black powder and the binding agent can subsequently be added together with a solvent mixture. However, it is also possible to first lace the solvent mixture with the nitrocellulose and then add the black powder and the binding agent. A mixture of 20 weight % of methanol and 50 weight % of acetone has proven itself as solvent, wherein the weight percentages for the solvent share always relate to the total weight of black powder, nitrocellulose and binding agent used.

[0010] Following the mixing of the starting batch, the respective mass is then distributed, e.g. in a corresponding mold, and is dried through heating, which causes the solvent to evaporate.

[0011] Further details and advantages of the invention follow from the exemplary embodiments, below which are explained with the aid of the Figures:

DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a block diagram for describing the production of a film-type ignition element according to the invention;

[0013]FIG. 2 is a view from above of a film-type ignition element having a smooth surface structure;

[0014]FIG. 3 is a view from above of a film-type ignition element with a net-type surface structure with openings; and

[0015]FIG. 4 is a cross section through a pipe-shaped ignition element.

REFERENCE NUMBER LIST

[0016] References numbers 1-4, in FIG. 1, refer to containers. Reference number 5 illustrates a mixer. Reference number 6 refers to shape, shape of the film. Reference number 7 relates to a forced-air oven. Reference numbers, 8, 8′, 8″ indicate the ignition element, film. Reference number 9 is a rib.

[0017] The invention will be described, in conjunction with figures, in the discussion which follows.

DETAILED DESCRIPTION

[0018]FIG. 1 shows a container 1 filled with black powder, a container 2 filled with nitrocellulose and a container 3 filled with a binding agent (e.g. dimethyl-phthalat) and a container 4 filled with a solvent.

[0019] To produce the ignition element, for example, 70 weight % of black powder, 10 weight % of nitrocellulose and 20 weight % binding agent are filled into a mixer 5 and are stirred with the aid of a stirring mechanism(s) that is not shown herein. Following the addition of 70 weight % of solvent (e.g. a mixture of 20 weight % methanol and 50 weight % acetone), the ingredients are mixed until a uniform, viscous mass results. The mixture is then filled into a corresponding film mold 6 and dried at approximately 60° C. inside a forced air oven 7. In the process, the solvent is evaporated.

[0020]FIG. 2 shows a film-type ignition element 8 after it is removed from the mold 6. This element can be bent, for example, to form a circular cylinder and can be inserted into a respective cartridge case (compare also to the aforementioned DE 43 18 740 C2).

[0021] The film 6 can be shaped in such a way that the ignition element 8′ has a net-type structure. As shown in FIG. 3, a net-type structure refers to an open meshed fabric. A net-type ignition element 8′ of this type has the advantage that the ignition can be controlled by varying the net structure. Depending on whether the net loops are narrow and/or wide, more or less of the ignition cartridge fuse material is available. Of course, the net-type structure can also be obtained by stamping out corresponding regions in the film 8, shown in FIG. 2.

[0022] The shape of the film 6 can furthermore be selected such that the ignition element 8″ represents a finished molded part, provided on the inside with radially arranged ribs 9 (compare FIG. 4). These ribs on the one hand stabilize the ignition element and, on the other hand, provide an additional surface for the ignition. 

What is claimed is:
 1. A film-type ignition element, for igniting the propellant charge of large-caliber ammunition, wherein the ignition element comprises more than 60 weight % black powder, less than 10 weight % nitrocellulose and at least 5 weight % of a plasticizer in the form of a binding agent.
 2. The film-type ignition element according to claim 1, wherein the black powder ranges between 63 and 85.5 weight %; the nitrocellulose ranges between 2.8 and 7 weight % and the binding agent ranges between 5 and 30 weight %.
 3. The film-type ignition element according to claim 1, wherein the binding agent is bis(2-ethyl)-phthalat, dimethyl-phthalat, Edenol B 33 or butyl-NENA.
 4. The film-type ignition element of claim 1, wherein the ignition element has a wall thickness ranging between 0.3 and 2.0 mm.
 5. The film-type ignition element according to claim 4, wherein the wall thickness of the ignition element is between 1 and 1.5 mm.
 6. The film-type ignition element according to claim 1, wherein the ignition element has a net-type structure.
 7. The film-type ignition element according to claim 1, wherein the ignition element is a finished molded part with radially inward-pointing ribs.
 8. A method for producing an ignition element according to claim 1, providing a composition comprising 63 to 85.5 weight % of black powder, 2.8 to 7 weight % nitrocellulose and 5 to 30 weight % of a binding agent and admixing said composition with approximately 70 weight % of a solvent to form a mixture; subsequently stirring said mixture until a uniform, viscous mass results; and processing said mass into a film or a shaped body.
 9. The method according to claim 8, wherein a mixture of 20 weight % methanol and 50 weight % acetone is used as solvent, wherein the weight percentage value is based on the total weight for black powder, nitrocellulose and binding agent used.
 10. An ignition element of claim 1, in the form of a flexible film.
 11. The ignition element of claim 1, which is in the form of a net.
 12. The ignition element of claim 1, in the form of a molded part comprising radially inward pointing ribs. 